July 7, 2025 — In the face of rising atmospheric carbon dioxide, the Gulf of Maine is thought to be particularly vulnerable to ocean acidification. Its vulnerability has to do with temperature: The waters of the gulf are cold, and cold water dissolves carbon dioxide more easily than warmer water does. Increased carbon dioxide decreases the pH of the ocean (making it more acidic), a concern for the health of the region’s ecosystems as well as its lucrative shellfish industry.
But determining seawater chemistry is complicated. It requires advanced equipment and the assessment of complex physical, chemical, and biological processes. Until now, no long-term data existed to put individual measurements into context, so scientists did not know how acidity in the region’s waters was trending.
Using ocean chemistry recorded in algae, researchers have now constructed a nearly 100-year history of acidity (pH) in the region. The analysis, published in Scientific Reports, shows that ocean acidification, seen around the world, has been delayed in the gulf.